Explosion-proof panelboard



Dec. 17, 1957 J. D. POMON ,8 6, 8

EXPLOSION-PROOF PANELBOARD Filed April 20, 1954 I 4 Sheets-Sheet 1 Dec. 17, 1957v J. D. POMON 2,816,678

EXPLOSION-PROOF PANELBOARD Filed April 20, 1954 4 Sheets-Sheet 2 l .L LZ Z: .4 c? .5 75 75 4454 44 u. 47

ILTLFEIZZU I [Jack .2). P0122022 Dec. 17, 1957 J. D. POMON 2,816,678

EXPLOSION-PROOF PANELBOARD Filed April 20, 1954 4 Sheets-Sheet 4 120 120 i l w 4 iil T- l 113 11g 112 m2 EIZEZZZLQT" .z/ack .22 P022022 United States Patent EXPLOSION-PROOF PANELBOARD Jack D. Pomon, Lombard, Ill., assignor to The Pyle- National Company, Chicago, 111., a corporation of New Jersey Application April 20, 1954, Serial No. 424,435 Claims. (Cl. 2203.94)

The present invention relates to an electrical installation device and more particularly to an explosionproof panelboard.

Still more particularly, the present invention relates to an explosion-proof panelboard having housings and closing terminal boards, switches, circuit breakers and the like.

Panelboards in industrial electrical installatlons frequently must be located in places where the surrounding atmosphere may become contaminated with inflammable or explosive gaseous mixtures. When so located, any sparks or arcs at the panelboard terminals or switches or circuit breakers would be highly dangerous and could cause fires and/or explosions resulting in great damage to property and danger, etc.

To obviate these dangers in accordince with the principles of the present invention, the article elements 1n the panelboard are enclosed in housings whlch are sub-- stantially explosion-proof and which prevent the escape of any hot gases which may have been heated above their kindling temperature by sparks or arcs within the housings. To this end, the various parts of the several housings of a panelboard incorporating the princ ples of the present invention are provided with interfitting grooved faces at substantially all of the junctions of the housing parts. The grooves in the faces run substantially transversely to the direction of flow of gas escaping from the housings at the junctions between the parts so that the gas flow will have to follow a tortuous path wh1ch 1s sufficiently extended to cool any escaping gas below its kindling temperature before it leaves the grooved interface between the parts. Thus, by providing tortuous interfaces between the various parts of the various housings, and between the various houses themselves, panelboards incorporating the principles of the present invention will be substantially explosion-proof and will not permit the escape of ignited or hot gases therefrom at higher than ignition temperatures.

It is therefore, an important object of the present invention to provide a new and improved electrical installation panelboard which is substantially explosionroof. p It is another important object of the present invention to provide a new and improved panelboard having a plurality of housings each comprising a plurality of parts assembled with tortuous interfaces. 7

Another important object of the present invention is to provide a new and improved explosion-proof panelboard for enclosing and encasing terminal boards, switches, and circuit breakers and the like in housings constructed from a plurality of sections having interfitting grooved faces to restrict the ingress and egress of fluids, particularly for the purpose of cooling flames and arcs to below ignition temperatures.

Still another object of the present invention is to provide a new and improved housing for explosion-proof panelboard when the housing comprises a body member and a cover member each having longitudinally grooved r 2,316,578 Ice Patented Dec. 17, 1

radial faces which interfit to provide a tortuous interface between the body member and the cover member.

Still another object of the present invention is to provide new and improved explosion-proof panelboard housings with substantially circumferentially concentrically grooved faces interfitting with similarly grooved faces on end plates to substantially seal the housings.

Still another object of the present invention is to provide a new and improved explosion-proof panelboard for terminal boards, switches and circuit breakers and the like with a plurality of interconnected housings.

Yet another object of the present invention is to provide a new and improved explosion-proof panelboard with a main housing and a plurality of transversely extending housings each of which are interconnected with the main housing.

Still other objects, features and advantages of the present invention will become readily apparent from the following detailed description of the present invention and a preferred embodiment thereof, from the claims, and from the drawings in which each and every detail shown is fully and completely disclosed as a part of this specificition, in which like reference numerals refer to like parts, and in which: a

Figure 1 is a front elevational view of an explosionproof panelboard incorporating the principles of the present invention and shown partially in vertical section and with certain parts partially broken away to more clearly illustrate certain features of the present invention;

Figure 2 is a longitudinal sectional view of the main housing assembly shown as taken substantially along the broken line IIII of Figure 1;

Figure 3 is a sectional view of the main housing assembly shown as taken substantially along the line III-Ill of Figure 2;

Figure 4 is a fragmental illustration of the interfitting relation between the body members and the end plate at an end of the main housing assembly as well as each of the various other housings;

Figure 5 is a longitudinal sectional view of a terminal housing assembly shown as taken substantially along the broken line VV of Figure 1 and further shown with a fragment thereof in elevation to illustrate certain features thereof;

Figure 6 is a transverse sectional view of a terminal housing assembly shown as taken substantially along the line VI-VI of Figure 1;

Figure 7 is a longitudinal sectional view of a circuit breaker housing assembly shown as taken substantially along the broken line VII-VII of Figure l; and

Figure 8 is a transverse sectional view of a circuit breaker housing assembly shown as taken substantially along the line VIIl-VIII of Figure 7.

As shown on the drawings:

In Figure 1 there is shown a complete explosion-proof panelboard 10 which is provided with a plurality of substantially sealed housings for terminal boards, switches and circuit breakers and the like assembled as a part of an electrical installation safely operable in regions where sparks or arcs or the like could cause fires or explosions, etc. The panelboard 10 has a main housing 11 which carries in assembly therewith a pair of transversely extending terminal housings 1212 and a set of circuit breaker housings 131313ll3. By way of example only and not way of any limitation on the present invention, the panelboard of Figure l is shown as having two terminal board housing assemblies 12 transversely disposed on opposite sides thereof in the region of its upper end and four circuit breaker housings 13 are disposed in pairs on opposite sides of the main housing 11 and in the central and lower regions thereof.

In this embodiment of the invention, main power busphase busses 15,. 16 and 17, respectively, are insulatingly supported and secured within the main housing assembly 11 for connection to main power leads (not shown) at main power connections to the bus bars such as solder-less lugs 18, 19, and 21, respectively.

In addition, each of the several bus bars are provided with further electrical connection means, such as terminal lugs 22 and/or additional solderless lugs such as may be secured thereto by screws 23, and illustrated in elevation in Figure 2 at 24. These additional terminal lugs, etc. provide means for connecting branch circuit loads through terminals in the terminal housing assemblies 12 and through the circuit breakers in the circuit breaker housings 13 to the main power leads connected to the bus bars 14, 15, 16 and 17 at the power lugs 18, 19, 20 and 21.

To insulatingly support the bus bars within the main housing assembly 11, the main housing assembly 11 has an elongated body provided with a back wall 26 and upstanding side walls 27 and 28. The longitudinally extending back wall 25 has an inwardly extending longitudinal leg or rib 29 and pairs of integral inwardly extending legs FAB-30 and 31-31. A pair of groups of insulating blocks 3232 carrying the bus bars 14 through 17, rest on the legs 30-30 and 31-31, respectively, and are secured to the longitudinally extending rib 29. Each of the groups of insulator blocks is provided with a first pair of blocks 33 and 34 having registering recesses to receive the bus bars 14 and 16 and pins 35 and 36 retaining the bus bars and the blocks in an assembled relation and preventing the bus bars from having longitudinal movement with respect to the insulator blocks. A spacer insulator block 37 spaces a second pair of insulator blocks 38 and 39 from the first pair of insulator blocks 33 and 34. These second pair of insulator blocks are also offset from the first pair and are recessed with registering recesses to receive the bus bars 15 and 17 and pins 40 and 41 extending through the bus bars and into the blocks to retain the bus bars in place. The offset relation between the pairs of insulator blocks provides for convenient connection to the bus bars and to the connecting lugs thereon.

To retain all of the several bus bars and insulator blocks in place on the legs and the rib which are integral with the back wall 26 of the body 25 of the main housing assembly 11, studs 42 are threaded into threaded bottomed stud receiving recesses 43 in the rib 29 while the studs 42 are axially arranged in insulating sleeves 44 passing through aligned apertures in the insulating blocks. Nuts 45 on the outer ends of the studs 42 retain the blocks and studs, etc. in place.

The main housing 11 which carries this main power connection bus bar assembly is, in accordance with the principles of the present invention, provided with an explosion proof construction by assembling therewith a cover member 46 having a front wall 47 and side walls 48 and 49 which are spaced for registration with the side walls 27 and 28 of the body 25 and are so arranged that when the cover 46 and the body 25 are secured together, ingress and egress of fluid through the interface between the cover walls and the body walls is substantially prevented.

To this end, the walls 27 and 28 of the body 25 are provided with substantially transverse or radial faces 50 and 51 which are longitudinally grooved preferably with substantially parallel grooves. The cover walls 48 and 49 are also provided with substantially transverse or radial faces 52 and 53 which are longitudinally preferably substantially parallel grooved in a manner whereby the grooved faces of the cover mate with the grooved faces of the body walls. Although these several grooved faces, and the various other grooved faces and surfaces hereinafter described in conjunction with various other parts of the explosive-proof panelboard herein described, are shown as having substantially square lands and grooves therein, they may have any other desired configuration of 75 lands and grooves such as arcuate grooves or V lands and grooves, etc., but it is preferred that the grooved faces of the cover walls interfit and mate with the grooved faces of the body walls in such a manner that the various segmental faces of the grooved faces prescribes a tortuous path longer than the thickness of the joint between the cover wall faces and the body wall faces, and of sufiicient length to cool any drawn arcs or flames below ignition temperatures.

With this arrangement any ignited or exploded gases or other fiuids within the main housing assembly will be required to follow a highly tortuous path over the tortuous interface between the cover member and the body member. In so traveling over this tortuous and extended path any ignited or exploded gases will be cooled below their kindling temperature before finally escaping from the main housing assembly if, indeed, they escape at all.

At the ends of the main housing assembly 11, similar tortuous interfaces are provided between upper and lower end plate retaining nuts 54 and 55, respectively, and the ends of the body 25 and cover 46. To this end, the body 25 is provided with integral end walls 56 and 57 having forwardly extending arcuate portions or similar circular portions 58 and 59, respectively (note Figure 3), which are received in the end Walls 60 and 61 of the cover 46. The end walls 58 and 59 of the body 46 extend axially outwardly from the main housing body 25 and are provided with internally and externally threaded axial bosses 62 and 63. The end plates or end plate retaining nuts 54 and 55 are provided with axially threaded apertures 64 and 65 which threadedly engage the external threads on the bosses 62 and 63 for sealing and locking engagement with the end faces of the body 25 and cover 46.

The end faces or outer faces of the end walls 56 and 57 of the body 25 and the outer faces of the end walls 60 and 61 of the cover 46 are substantially peripherally grooved with grooves similar to those in the faces 50, 51, 52 and 53 of the body side walls and cover side walls but are further substantially concentric with the bosses 62 and 63. The inner faces of the nuts or end plates 54 and 55 are similarly concentrically grooved with similarly shaped lands and grooves to provide tortuous interfaces 66 and 67 between the end plate 54 and the body 25 and cover 46, and between the end plate 55 and the body 25 and the cover 46.

By providing a plurality of turns in threaded engagement between the nuts 54 and 55 in the bosses 62 and 63, respectively, tortuous interfaces are also provided at that locale which together with the interfaces 66 and 67 substantially prevent fluid flow outwardly from the ends of the main housing assembly 11.

Thus the end plate retaining nuts 54 and 55 not only operate to substantially explosion-proof seal the ends of the main housing assembly 11 but further act to sealingly retain the cover 46 on the body 25. To enhance the sealing and explosion-proof relation between the end plates and the body and the cover of this assembly, however, and in accordance with the principles of the present invention, the grooves in the interfaces 66 and 67 are staggered with respect to the grooves and tortuous interfaces between the side walls of the body and the cover. This staggered relationship is particularly shown in the enlarged fragmental illustration of Figure 4 wherein a portion of the side wall 28 and end wall 58 is shown in assembled relation with the end plate retaining nut 54 particularly at the junction of the tortuous interfaces.

In this figure it will beobserved that the inner face 68 of the end plate 54 is provided. with concentric lands 69 andconcentric grooves 70 which mate with concentric grooves 71 and concentric lands 72 in the end face of the end wall or the outer face of the end wall 58. These lands and grooves, however, are substantially half-width offset from the lands and grooves in the grooved face 51 of the side wall 28 and are, therefore, half-width offset or staggered from the lands and grooves in the side wall 49 of the cover 46 which make their width as shown in Figure 3. With this staggered interfitting relation explosion-proof sealing of the housing 11 is greatly enhanced since the tortuous path for fluid flow at the end walls and at the junction of the three sections 26, 46 and 54 is increased.

Since power cables are to be brought into the main housing assembly 11 for the actual connection to the several bus bars, the end walls 62 and 63 are provided with such apertures as apertures 73 and 74 thereby permitting entry to the main housing assembly from either end thereof. Any thereof which are not utilized may be sealed wtih such convenient means as a pipe plug 75 or the like. The apertures 73 and 74 are also provided with annular recesses 76 and 77 whereby sealing cement which may be employed to surround the inlet cables within the apertures 73 and 74 to seal the openings in the main housing assembly 11, will be properly retained in place.

In accordance with good engineering practice and principles, the main housing assembly 11 is also provided with a breather assembly 78 sealingly secured in an appropriate aperture 79 in one end wall, preferably the upper end wall, and a water drain assembly 80 is fixed in an appropriate aperture 81 in the other end wall, preferably the lower end wall. Since neither the breather assembly nor the water drain assembly form any specific part of the present invention, neither of them will be described in great detail. Each of the other several panelboard may be provided with such breathers and drains also.

The walls 27 and 28 of the body 25 of the main housing assembly 11 are provided with a plurality of threaded apertures 73' for threadable acceptance of internally and externally threaded nuts 74' for attachment of nipples 75 thereto to retain the terminal housing assemblies 12 in firm assembly with the main housing assembly 11 in the panelboard l and in explosion-proof assembly therewith. Each of the terminal housing assemblies 12 is substantially symmetrically identical to the other of the same and each is provided with a body 76 (Figure having a pair of threaded apertures 77 in an end wall 79' thereof for threaded acceptance of the nipples 75'. Threaded apertures 77 are also provided with annular shoulder recesses 78 to retain sealing cement disposed within the nipples and the apertures and about electrical lead wires and the like extending between the main housing assembly 11 and the terminal housings 12.

Similar apertures 78a in the opposite end wall 80' (Figure 6) may be sealed by threaded plug members or the like and may be readily removed if the apertures are to be used for conduit connections.

The terminal housing assembly body 76' is provided with a back wall 81 and side walls 82--83 which are integral with the end walls 79 and 80', and legs 83 are formed internally and integrally on the inner face of the back wall 81. These legs 83 carry an insulated terminal block assembly 34 of any desired design and construction and which is secured to the legs 83. Branch outlet apertures 85 provide for inlet and outlet leads for connection to the terminal block assembly 84 and are constructed with an internal peripheral recess, etc. 86 for retaining sealing cement or the like filling the apertures 85 surrounding the lead wires extending therethrough.

Explosion-proof sealing of the terminal housing assembly is accomplished in accordance with the principles of the present invention substantially in the same manner as hereinabove described for the main housing assembly ll. That is, the walls 82 have outer radial faces 8787 which are provided with longitudinal lands and grooves extending for the full length of the side walls 8282. A cover member 88 is also provided with side walls 89-- 89 having longitudinally extending radial faces 9090 which are longitudinally grooved with lands and grooves interfitting with the grooves and lands in the radial faces 87 0f the body 76. The radial faces 90 so interfit with the grooved radial faces 87 that there is a substantially sealing relation therebetween and a tortuous interface therebetween of sufiicient length to cool any gases tending to flow over the interface between the body and the cover.

At the ends of the terminal housing assembly, the side walls 82-82 of the body 76' extend outwardly beyond the end walls 79' and but not beyond outwardly extending substantially similar circular boss portions 91 on the outer face of the end walls 79 and 80'. These boss portions 91 are provided with substantially circumferential and substantially concentric lands and grooves which register with substantially peripheral and substantially semi-circular and concentric lands and grooves of the end faces 92 of the cover 88.

These registered concentric grooves in the end face of the bosses 91 and the end face 92 of the cover 88 are offset from the grooves in the radial faces 87 and of the body 76 and cover 33, respectively, in the manner as shown in Figure 4 for the end walls, etc. of the main housing assembly ll.

End plates or retaining nuts 93-93 threadably engage internally threaded apertures 94 extending axially through substantially semi-circular outstanding portions 95 of the end walls 79 and 80. These end cover retaining nuts 93 are also provided with outer flange portions 96 having grooved inner faces 97 which mate with the lands and grooves in the boss 91 and the end faces of the cover 88, thereby substantially explosion-proof sealing the ends of the terminal housing assembly 12.

Thus, any arcs or sparks from electrical leads connected to the various terminals 98 of the terminal block 99 or to the neutral strip 160, which could cause ignition or explosion of gases within the terminal housing assembly 12 would fail to cause any ignition or explosion of gases without the terminal housing assembly 12 since gas flow through the interfaces of the various sections of the terminal housing assembly would necessarily follow such a tortuous path as to be cooled below its ignition temperature before actually escaping.

The breaker housing assemblies 13 are similarly constructed to explosion-proof seal the contents thereof. These breaker housing assemblies 13 are provided with body sections 101 having a back wall N2, the inner face of which has legs 163 for attachment and firm assembly mounting of circuit breaker and/or switch units and the like as shown at 104 which are to be electrically connected between the terminal board assembly $4 and the bus bars and the like within the main housing assembly for protective connection between the main power lines and the branch circuits in power distribution systems.

As an exemplary illustration, in Figure 7 leads 105 are shown connected to the switches or breakers or the like 104 and leading through the central hubbed aperture 106 in the attachment nut 167 which securely mounts the breaker housing assembly 13 on the main housing assembly 11 and which is threaded into an aperture N8 in the main housing assembly and provided therefor. The aperture 106 in the attachment nut 107 is preferably provided with an annular recess 109 and annular flanges 110 so that the sealing cement llll or the like surrounding the leads 195 within the aperture 166 will sealingly be retained within the aperture 166.

The body 101 of the breaker or switch housing assembly 13 is provided also with side walls 112 having longitudinally grooved radial faces 1 .13 and slightly inwardly disposed end walls 114 and M5 which are substantially axially apertured as at 116 and 117, respectively, to receive the end cover plates and attachment nuts and retaining nuts 107 and 118, respectively.

The cover section 119 which carries the switch operators or breaker operators 120 also has side walls 121 which have longitudinally grooved radial faces 122 for making cooperation with the grooved faces 113 of the body 101 so as to provide a tortuous interface between the body section 101 and the cover section 119.

At the end extremities of the body 101 and the cover 119, boss-like portions 123 and 124 are provided with registering substantially peripheral and substantially concentric land and groove outer faces 125 and 126 which register with each other and which register with the grooved faces 113 and 122 of the body and cover substantially in the same manner as shown in Figure 4 for the main housing assembly 11. The aperture 117 in the end wall 115 is threaded for threaded and sealing reception of the plug portion 127 of the retaining nut and end plate 118 while a flange 128 on the member 118 is provided with a grooved inner face 129 which mates with the grooved faces 125 and 126 to seal the breaker and switch housing assembly 13 and retains the cover 119 on the body 101. At the other end of the switch and breaker housing assembly 13, the attachment nut 107 is provided with a radial flange 130 having a grooved inner face 131 which mates with the grooves 125 and 126 to substantially explosion-proof seal at that end of the assembly 13.

To retain the attachment nut 107 against the body and the end cover a lock nut 132 or the like firmly abuts the inner face of the end wall 114 and threadedly engages the attachment nut 107.

This complete arrangement for the switch or breaker housing assembly 13 will provide substantially explosionproof protection against any arcs or sparks or the like which may occur at the switches or breakers or the like 104 when they open or close the various circuits in which they may be connected.

From the foregoing it will be observed that numerous variations and modifications may be effected in the designs and arrangements of an explosion-proof panelboard or the like incorporating the principles of the present invention without departing from the true spirit and scope of the present invention. 1, therefore, intend to cover all such modifications and variations as fall within the true spirit and scope of the novel concepts and the principles of my invention.

I claim as my invention:

1. In an explosion-proof panelboard to enclose switches and circuit breakers and terminals and the like where the atmosphere may be inflammable or explosive, a housing having a body section and a cover section, each of said sections having radial faces provided with a plurality of longitudinally extending grooves, the grooves in said radial faces interfitting to provide a tortuous path for gas flow into and out of said housings between said body section and said cover section, end faces on said sections provided with substantially circumferential concentric grooves offset from said longitudinal grooves, and end plates provided with concentric grooves interfitting with the grooves in the end faces of said sections to provide a tortuous path for gas flow into and out of said housings between said sections and said end plates.

2. In an explosion-proof panelboard to enclose switches and circuit breakers and terminals and the like where the atmosphere may be inflammable or eX- plosive, a housing having a body section and a cover section, each of said sections having radial faces provided with a plurality of longitudinally extending grooves, the grooves in said radial faces interfitting to provide a tortuous path for gas flow into and out of said housings between said body section and said cover section, end faces on said sections provided with substantially circumferential concentric grooves olfset from the longitudinal grooves, and end plates provided with concentric grooves interfitting with the grooves in the end faces of said sections offset from said grooves in said radial faces to provide a tortuous path for gas flow at the intersection of the sets of grooves.

3. In an explosion-proof panelboard having a plurality of housings each of which is assembled from a plurality of sections, the sections for each of said housings comprising a pair of semi-enclosing shells and a pair of end caps, interfitting grooved radial faces on said shells at junctions therebetween, grooved radial end faces on said shells having grooves which are staggered with respect to the grooves in the grooved radial faces on said shells, and grooved radial faces on said caps interfitting with the grooved end faces on said shells, whereby there is provided a tortuous path for gas fiow into and out of said housings.

4. In an explosion-proof housing assembly for an electrical installation, a housing body, side walls on said body and longitudinally grooved radial faces on said side walls of said body, a housing cover, side walls on said cover, and longitudinally grooved radial faces on said side walls of said cover, said grooved faces mating to form tortuous interfaces between said body of said cover, substantially concentrically grooved end faces on said body and said cover having grooves which are staggered with respect to the grooves on said radial faces, and an end cover plate assembled therewith, and substantially concentric grooves in said end cover plate interfitting with the grooved end faces of said body and said cover.

5. In an explosion-proof housing assembly for an electrical installation, a housing body, side walls on said body and longitudinally grooved radial faces on said side walls of said body, a housing cover, side walls on said cover, and longitudinally grooved radial faces on said side walls of said cover, said grooved faces mating to form tortuous interfaces between said body of said cover, an apertured end wall on said body, registering circumferential substantially concentric grooves on said end wall and said cover which are staggered with respect to the grooves of said radial faces, and an end plate secured on said end wall and substantially concentric grooves in said plate mating with said grooves in said end wall and said cover.

References Cited in the file of this patent UNITED STATES PATENTS 150,536 Crosby May 5, 1874 608,412 Patten et al. Aug. 2, 1898 963,248 Ramelli July 5, 1910 1,101,892 Vibber June 30, 1914 1,331,986 Grifiin Feb. 24, 1920 1,754,776 Stanley Apr. 15, 1930 2,208,558 Appleton July 23, 1940 2,511,889, Weiss June 20, 1950 FOREIGN PATENTS 617,871 Germany Aug. 29, 1935 

